Development and Application of Asymmetric Organocatalytic Mukaiyama and Vinylogous Mukaiyama‐Type Reactions

Frías, María A.; Cieślik, Wioleta; Fraile, Alberto; Rosado‐Abón, Anielka; Garrido‐Castro, Alberto F.; Yuste, Francisco; Alemán, José V.

doi:10.1002/chem.201801866

Cited by 44 publications

(23 citation statements)

References 146 publications

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“…[91][92][93] Similarly, acetate ions triggered the Michael reactions of 1b and 1-(trimethylsiloxy)cyclohexene (9c) with chalcone (13) (Scheme 16b). [94][95][96] Reetz reported the synthesis of α-tert-alkyl-substituted carbonyl compounds by Lewis acid mediated reactions of silyl enol ethers with tert-alkyl chlorides or acetates (Scheme 17). [97][98][99]…”

Section: Feature Syn Thesismentioning

confidence: 99%

Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Leonov¹,

Timofeeva²,

Ofial

et al. 2019

Synthesis

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The kinetics of the reactions of trimethylsilyl enol ethers and enamines (derived from deoxybenzoin, indane-1-one, and α-tetralone) with reference electrophiles (p-quinone methides, benzhydrylium and indolylbenzylium ions) were measured by conventional and stopped-flow photometry in acetonitrile at 20 °C. The resulting second-order rate constants were subjected to a least-squares minimization based on the correlation equation lg k = s N(N + E) for determining the reactivity descriptors N and s N of the silyl enol ethers and enamines. The relative reactivities of structurally analogous silyl enol ethers, enamines, and enolate anions towards carbon-centered electrophiles are determined as 1, 107, and 1014, respectively. A survey of synthetic applications of enolate ions and their synthetic equivalents shows that their behavior can be properly described by their nucleophilicity parameters, which therefore can be used for designing novel synthetic transformations.

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Section: Feature Syn Thesismentioning

confidence: 99%

Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Leonov¹,

Timofeeva²,

Ofial

et al. 2019

Synthesis

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“…Compared to the intensive research on enolization of carbonyl compounds, the dienolization of linear α,β‐unsaturated compounds is much less investigated except for some special substrates. [ 6‐11 ] Utilization of these dienolates in organic synthesis would result in synthetically powerful vinylogous reaction. [ 6‐11 ] Generally speaking, the dienolization of linear α,β‐unsaturated ketones, esters, and amides is very challenging in the presence of a common organic base due to the high p K a value of the γ‐protons.…”

Section: Background and Originality Contentmentioning

confidence: 99%

“…[ 6‐11 ] Utilization of these dienolates in organic synthesis would result in synthetically powerful vinylogous reaction. [ 6‐11 ] Generally speaking, the dienolization of linear α,β‐unsaturated ketones, esters, and amides is very challenging in the presence of a common organic base due to the high p K a value of the γ‐protons. Therefore, linear β,γ‐unsaturated compounds are employed in asymmetric catalysis to facilitate the generation of the corresponding dienolates by means of the relatively low p K a value of α‐protons (Scheme 1a).…”

Section: Background and Originality Contentmentioning

confidence: 99%

Catalytic Asymmetric Mannich‐Type Reaction Enabled by Efficient Dienolization of α,β‐Unsaturated Pyrazoleamides†

et al. 2020

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Asymmetric catalysis | Vinylogous reaction | Pyrazoleamide | Copper catalyst | Dienolization (E)-α,β-Unsaturated pyrazoleamides undergo facile dienolization to furnish copper(I)-(1Z,3Z)-dienolates as the major in the presence of a copper(I)-(R)-DTBM-SEGPHOS catalyst and Et 3 N, which react with aldimines to afford syn-vinylogous products as the major diastereoisomers in high regio-and enantioselectivities. In some cases, the diastereoselectivity is low, possibly due to the low ratio of copper(I)-(1Z,3Z)-dienolates to copper(I)-(1Z,3E)-dienolates. (Z)-Allylcopper(I) species is proposed as effective intermediates, which may form an equilibrium with copper(I)-(1Z,3Z)-dienolates. Interestingly, the present methodology is a nice complement to our previous report, in which (E)-β,γ-unsaturated pyrazoleamides were employed as the prenucleophiles in the copper(I)-catalyzed asymmetric vinylogous Mannich-Type reaction and anti-vinylogous products were obtained. In the previous reaction, copper(I)-(1Z,3E)-dienolates were generated through α-deprotonation, which might form an equilibrium with (E)-allylcopper(I) species. Therefore, it is realized in the presence of a copper(I) catalyst that (E)-α,β-unsaturated pyrazoleamides lead to syn-products and (E)-β,γ-unsaturated pyrazoleamides lead to anti-products. Finally, by use of (E)-β,γ-unsaturated pyrazoleamide, (E)-α,β-unsaturated pyrazoleamide, (R)-DTBM-SEGPHOS, and (S)-DTBM-SEGPHOS, the stereodivergent synthesis of all four stereoisomers is successfully carried out. Then by following a three-step reaction sequence, all four stereoisomers of N-Boc-2-Ph-3-Me-piperidine are synthesized in good yields, which potentially serve as common structure units in pharmaceutically active compounds.

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“…Acid catalysis is most frequently used in organic synthesis by activating electrophiles with a variety of Lewis acids, such as proton donors and various metal ions. [1][2][3][4][5][6][7][8][9][10][11][12][13] According to Gilbert Newton Lewis, 14 an acid is an electron pair acceptor. This concept is more general than that by Johannes Nicolaus Brønsted, who defined that an acid is a molecule that can donate protons.…”

Section: Introductionmentioning

confidence: 99%

Acid Catalysis via Acid‐Promoted Electron Transfer

Fukuzumi

Lee

Nam

2020

Bulletin Korean Chem Soc

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This feature article focuses on acid catalysis in various redox reactions of not only organic compounds but also metal complexes, in particular metal-oxygen complexes via acid-promoted electron transfer (APET). On the other hand, proton-coupled electron transfer (PCET) has been extensively studied in relation with important biological PCET reactions such as O 2 reduction in respiration and water oxidation in photosynthesis. Because PCET is normally defined as simultaneous electron and proton transfer from the same substrate, acid-promoted electron transfer using external acids is called APET in this article. Various types of chemical transformations exhibiting acid catalysis via APET discussed in this article include C C bond formation, C H bond oxidation, aromatic hydroxylation, and oxygen atom transfer reactions such as sulfoxidation and epoxidation reactions.

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Development and Application of Asymmetric Organocatalytic Mukaiyama and Vinylogous Mukaiyama‐Type Reactions

Cited by 44 publications

References 146 publications

Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Metal Enolates – Enamines – Enol Ethers: How Do Enolate Equivalents Differ in Nucleophilic Reactivity?

Catalytic Asymmetric Mannich‐Type Reaction Enabled by Efficient Dienolization of α,β‐Unsaturated Pyrazoleamides†

Acid Catalysis via Acid‐Promoted Electron Transfer

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